首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   76448篇
  免费   5685篇
  国内免费   390篇
耳鼻咽喉   754篇
儿科学   1827篇
妇产科学   1724篇
基础医学   9658篇
口腔科学   1944篇
临床医学   7671篇
内科学   17563篇
皮肤病学   1003篇
神经病学   6173篇
特种医学   2288篇
外国民族医学   2篇
外科学   11768篇
综合类   1140篇
现状与发展   1篇
一般理论   116篇
预防医学   6427篇
眼科学   2092篇
药学   5301篇
中国医学   152篇
肿瘤学   4919篇
  2023年   372篇
  2022年   583篇
  2021年   1614篇
  2020年   935篇
  2019年   1382篇
  2018年   1629篇
  2017年   1130篇
  2016年   1269篇
  2015年   1487篇
  2014年   2255篇
  2013年   3439篇
  2012年   4757篇
  2011年   5083篇
  2010年   2900篇
  2009年   2710篇
  2008年   4835篇
  2007年   5086篇
  2006年   4853篇
  2005年   5018篇
  2004年   4675篇
  2003年   4164篇
  2002年   4069篇
  2001年   861篇
  2000年   727篇
  1999年   847篇
  1998年   896篇
  1997年   723篇
  1996年   590篇
  1995年   587篇
  1994年   541篇
  1993年   508篇
  1992年   585篇
  1991年   553篇
  1990年   472篇
  1989年   491篇
  1988年   451篇
  1987年   431篇
  1986年   413篇
  1985年   466篇
  1984年   487篇
  1983年   447篇
  1982年   584篇
  1981年   477篇
  1980年   514篇
  1979年   341篇
  1978年   334篇
  1977年   351篇
  1976年   285篇
  1975年   299篇
  1974年   260篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Objective

The aim of the study was to estimate the effect of the state-based reinsurance programs through the section 1332 State Innovation Waivers on health insurance marketplace premiums and insurer participation.

Data Source

2015 to 2022 Robert Wood Johnson Foundation Health Insurance Exchange Compare Datasets.

Study Design

An event study difference-in-differences (DD) model separately for each year of implementation and a synthetic control method (SCM) are used to estimate year-by-year effects following program implementation.

Data Collection/Extraction Methods

Not applicable.

Principal Findings

Reinsurance programs were associated with a decline in premiums in the first year of implementation by 10%–13%, 5%–19%, and 11%–17% for bronze, silver, and gold plans (p < 0.05). There is a trend of sustained declines especially for states that implemented their programs in 2019 and 2020. The SCM analyses suggest some effect heterogeneity across states but also premium declines across most states. There is no evidence that reinsurance programs affected insurer participation.

Conclusion

State-based reinsurance programs have the potential to improve the affordability of health insurance coverage. However, reinsurance programs do not appear to have had an effect on insurer participation, highlighting the need for policy makers to consider complementary strategies to encourage insurer participation.  相似文献   
2.
International Ophthalmology - To investigate the efficacy and safety of non-valved Aurolab aqueous drainage implant (AADI) surgery combined with phacoemulsification in eyes with refractory glaucoma...  相似文献   
3.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
4.
5.
6.
7.
8.
9.
10.
Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号